cmdxray / commands

Shell commands, explained

Plain-English breakdowns of 161 common commands — every flag, real examples, token by token. Or paste your own command into the offline explainer.

▸ Popular one-liners, explained → ⚠ Dangerous commands, explained →

aliasdefine or display command shortcuts (shell builtin)aptinstall and manage Debian/Ubuntu packages atschedule a command to run once at a specified later time awkpattern-scanning and text-processing language awscommand-line interface for Amazon Web Services base64encode or decode data in Base64 basenamestrip the directory (and optionally a suffix) from a path, leaving the file name bzip2compress or decompress files with the Burrows-Wheeler algorithm (.bz2)cargothe Rust package manager and build tool catconcatenate files and print them chattrchange ext2/3/4 file attributes, e.g. +i makes a file immutable chmodchange file mode (permission) bits chownchange file owner and group columnformat input into neatly aligned columns commcompare two SORTED files line by line, in three columns cpcopy files or directories crontabinstall, view, or edit a user's scheduled (cron) jobs curltransfer data to or from a URL cutextract selected columns from each line dateprint or set the system date and time ddcopy and convert data block by block dfreport free space on mounted filesystems diffcompare two files line by line and show the differences digquery DNS name servers (a DNS lookup tool)dirnamestrip the last component from a path, leaving the directory portion dmesgprint or control the kernel ring buffer (boot and driver messages)dockerbuild, run and manage containers duestimate file and directory disk usage echoprint text to standard output envshow the environment, or run a command with a modified one exportmark shell variables for export to child processes (shell builtin)ffmpegrecord, convert and stream audio and video fileidentify a file's type by inspecting its contents, not its name findwalk a directory tree looking for files firewall-cmdmanage firewalld — the dynamic firewall daemon on RHEL/Fedora systems foldwrap each input line to a given width freeshow memory and swap usage gcloudthe Google Cloud CLI getfacldisplay the Access Control Lists (ACLs) of files and directories ghthe official GitHub CLI gitthe distributed version control system gothe Go toolchain — build, test, and manage Go code gpgGNU Privacy Guard — encrypt, decrypt, and sign data grepsearch input for lines matching a pattern groupaddcreate a new group gunzipdecompress .gz files created by gzip gzipcompress files with gzip (replaces the original with .gz)headprint the first part of files historydisplay or manage the shell command history (shell builtin)hostnameshow or set the system's host name hostnamectlquery and change the system hostname and related metadata htopinteractive process and resource viewer (a friendlier `top`)idprint user and group identity (UID, GID, groups)ifconfigconfigure or display network-interface settings (legacy; prefer `ip`)ipshow / manipulate routing, network devices, interfaces and tunnels iptablesadminister the Linux kernel IPv4 packet-filter rules (netfilter firewall)joinjoin the lines of two files that share a common field journalctlquery and display logs from the systemd journal jqcommand-line JSON processor (apply a filter to JSON input)killsend a signal to a process killallkill all processes matching a given name kubectlcontrol a Kubernetes cluster lddprint the shared libraries a program or library depends on lessview text one screen at a time (a pager)lnmake links between files lslist directory contents lsblklist block devices (disks and their partitions) as a tree lscpudisplay information about the CPU architecture lsmodshow the status of loaded kernel modules (reads /proc/modules)lsoflist open files (and the processes that hold them open)lspcilist all PCI devices lsusblist USB buses and the devices connected to them ltracetrace the library (and optionally system) calls a program makes makebuild targets according to a Makefile mandisplay the on-line manual page for a command md5sumcompute or verify MD5 checksums (128-bit; use sha256sum for security)mkdircreate directories mktempsafely create a unique temporary file or directory and print its name modprobeadd or remove modules from the Linux kernel mountattach a filesystem to the directory tree (or list current mounts)mvmove or rename files and directories nanoa simple, friendly terminal text editor ncopen, listen on, or script raw TCP/UDP connections (netcat)netstatshow network connections, routing tables, and interface stats nicerun a program with a modified scheduling priority (niceness)nlnumber the lines of a file as it writes them out nohuprun a command immune to hangups, ignoring SIGHUP so it survives logout npmthe Node.js package manager nslookupquery DNS name servers for a domain's records interactively or in one shot opensslOpenSSL — command-line cryptography and TLS toolkit passwdchange a user's password (and password-aging settings)pastemerge lines of files side by side, separated by tabs pingtest reachability of a host on the network pipthe Python package installer pkillsignal processes selected by name or attribute — no PID needed pnpma fast, disk-efficient Node.js package manager printfformat and print data using a printf-style template psreport a snapshot of running processes pythonthe Python interpreter realpathresolve a path to its absolute, symlink-free canonical form renicechange the scheduling priority of already-running processes revreverse the order of characters on every line rmremove files or directories rsyncefficiently sync files, copying only what changed scpcopy files between hosts over SSH screenterminal multiplexer — detachable sessions that survive logout sedstream editor — transform text line by line seqprint a sequence of numbers, from FIRST to LAST sftpinteractive secure file transfer over SSH sha1sumcompute or check SHA-1 (160-bit) checksums of files sha256sumcompute or verify SHA-256 checksums sha512sumcompute or verify SHA-512 checksums shufwrite a random permutation of its input lines sleeppause for a given amount of time before returning sortsort lines of text splitsplit a file into fixed-size or fixed-count pieces ssinspect sockets (a faster, modern replacement for netstat)sshlog in to or run a command on a remote machine ssh-copy-idinstall your public SSH key into a remote host's authorized_keys ssh-keygengenerate, manage and convert SSH authentication keys statdisplay detailed file status — size, permissions, timestamps, inode stracetrace the system calls and signals a process makes stringsprint the printable character sequences found in a file suswitch to another user and start a shell (defaults to root)sudorun a command as another user (root by default)systemctlcontrol the systemd init system and its services systemd-analyzeinspect and profile systemd boot performance and unit state tacconcatenate and print files in reverse — last line first tailprint the last part of files tararchive utility — bundle files into (or extract them from) a .tar tasksetset or read a process's CPU affinity (which cores it may use)teecopy input to a file and pass it through to output too terraforminfrastructure-as-code provisioning tool timedatectlquery and change the system clock, time zone and NTP settings timeoutrun a command, killing it if it runs longer than a time limit tmuxterminal multiplexer — persistent sessions with split panes topshow a live, sorted view of running processes touchcreate empty files, or update a file's access/modification times trtranslate or delete characters traceroutetrace the network hops (routers) packets take to reach a host treelist directory contents as an indented tree ufwUncomplicated Firewall — a friendly front-end for the iptables firewall umountdetach (unmount) a mounted filesystem unameprint system and kernel information uniqreport or omit repeated adjacent lines unzipextract files from a ZIP archive uptimeshow how long the system has been running plus load averages useraddcreate a new user account usermodmodify an existing user account vimVi IMproved — a modal terminal text editor watchrun a command repeatedly and watch its output update wccount lines, words and bytes wgetdownload files from the web over HTTP/FTP whichlocate a command — print the full path of the executable that would run whoshow who is currently logged in whoamiprint the effective user name of the current user xargsbuild and run command lines from standard input xzcompress or decompress files with the LZMA2 algorithm (.xz)yarnan alternative Node.js package manager zcatdecompress gzip-compressed files and write the result to stdout zippackage and compress files into a .zip archive

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